/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package com.googlecode.bluetools.dom4j.util;

import java.util.Comparator;

import com.googlecode.bluetools.dom4j.Attribute;
import com.googlecode.bluetools.dom4j.Branch;
import com.googlecode.bluetools.dom4j.CDATA;
import com.googlecode.bluetools.dom4j.CharacterData;
import com.googlecode.bluetools.dom4j.Comment;
import com.googlecode.bluetools.dom4j.Document;
import com.googlecode.bluetools.dom4j.DocumentType;
import com.googlecode.bluetools.dom4j.Element;
import com.googlecode.bluetools.dom4j.Entity;
import com.googlecode.bluetools.dom4j.Namespace;
import com.googlecode.bluetools.dom4j.Node;
import com.googlecode.bluetools.dom4j.ProcessingInstruction;
import com.googlecode.bluetools.dom4j.QName;
import com.googlecode.bluetools.dom4j.Text;

/**
 * <p>
 * <code>NodeComparator</code> is a {@link Comparator}of Node instances which is capable of comparing Nodes for equality
 * based on their values.
 * </p>
 * 
 * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
 * @version $Revision: 1.1 $
 */
public class NodeComparator implements Comparator {
	/**
	 * Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first
	 * argument is less than, equal to, or greater than the second.
	 * 
	 * <p>
	 * The implementor must ensure that <tt>sgn(compare(x, y)) ==
	 * -sgn(compare(y, x))</tt> for all <tt>x</tt> and <tt>y</tt>. (This implies that <tt>compare(x, y)</tt> must throw
	 * an exception if and only if <tt>compare(y, x)</tt> throws an exception.)
	 * </p>
	 * 
	 * <p>
	 * The implementor must also ensure that the relation is transitive:
	 * <tt>((compare(x, y)&gt;0) &amp;&amp; (compare(y, z)&gt;0))</tt> implies <tt>compare(x, z)&gt;0</tt>.
	 * </p>
	 * 
	 * <p>
	 * Finally, the implementer must ensure that <tt>compare(x, y)==0</tt> implies that
	 * <tt>sgn(compare(x, z))==sgn(compare(y, z))</tt> for all <tt>z</tt>.
	 * </p>
	 * 
	 * <p>
	 * It is generally the case, but <i>not </i> strictly required that <tt>(compare(x, y)==0) == (x.equals(y))</tt>.
	 * Generally speaking, any comparator that violates this condition should clearly indicate this fact. The
	 * recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."
	 * </p>
	 * 
	 * @param o1 the first object to be compared.
	 * @param o2 the second object to be compared.
	 * 
	 * @return a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater
	 *         than the second.
	 */
	public int compare(Object o1, Object o2) {
		if (o1 == o2) {
			return 0;
		}
		else if (o1 == null) {
			// null is less
			return -1;
		}
		else if (o2 == null) {
			return 1;
		}

		if (o1 instanceof Node) {
			if (o2 instanceof Node) {
				return compare((Node) o1, (Node) o2);
			}
			else {
				// Node implementations are greater
				return 1;
			}
		}
		else {
			if (o2 instanceof Node) {
				// Node implementations are greater
				return -1;
			}
			else {
				if (o1 instanceof Comparable) {
					Comparable c1 = (Comparable) o1;

					return c1.compareTo(o2);
				}
				else {
					String name1 = o1.getClass().getName();
					String name2 = o2.getClass().getName();

					return name1.compareTo(name2);
				}
			}
		}
	}

	public int compare(Node n1, Node n2) {
		int nodeType1 = n1.getNodeType();
		int nodeType2 = n2.getNodeType();
		int answer = nodeType1 - nodeType2;

		if (answer != 0) {
			return answer;
		}
		else {
			switch (nodeType1) {
			case Node.ELEMENT_NODE:
				return compare((Element) n1, (Element) n2);

			case Node.DOCUMENT_NODE:
				return compare((Document) n1, (Document) n2);

			case Node.ATTRIBUTE_NODE:
				return compare((Attribute) n1, (Attribute) n2);

			case Node.TEXT_NODE:
				return compare((Text) n1, (Text) n2);

			case Node.CDATA_SECTION_NODE:
				return compare((CDATA) n1, (CDATA) n2);

			case Node.ENTITY_REFERENCE_NODE:
				return compare((Entity) n1, (Entity) n2);

			case Node.PROCESSING_INSTRUCTION_NODE:
				return compare((ProcessingInstruction) n1, (ProcessingInstruction) n2);

			case Node.COMMENT_NODE:
				return compare((Comment) n1, (Comment) n2);

			case Node.DOCUMENT_TYPE_NODE:
				return compare((DocumentType) n1, (DocumentType) n2);

			case Node.NAMESPACE_NODE:
				return compare((Namespace) n1, (Namespace) n2);

			default:
				throw new RuntimeException("Invalid node types. node1: " + n1 + " and node2: " + n2);
			}
		}
	}

	public int compare(Document n1, Document n2) {
		int answer = compare(n1.getDocType(), n2.getDocType());

		if (answer == 0) {
			answer = compareContent(n1, n2);
		}

		return answer;
	}

	public int compare(Element n1, Element n2) {
		int answer = compare(n1.getQName(), n2.getQName());

		if (answer == 0) {
			// lets compare attributes
			int c1 = n1.attributeCount();
			int c2 = n2.attributeCount();
			answer = c1 - c2;

			if (answer == 0) {
				for (int i = 0; i < c1; i++) {
					Attribute a1 = n1.attribute(i);
					Attribute a2 = n2.attribute(a1.getQName());
					answer = compare(a1, a2);

					if (answer != 0) {
						return answer;
					}
				}

				answer = compareContent(n1, n2);
			}
		}

		return answer;
	}

	public int compare(Attribute n1, Attribute n2) {
		int answer = compare(n1.getQName(), n2.getQName());

		if (answer == 0) {
			answer = compare(n1.getValue(), n2.getValue());
		}

		return answer;
	}

	public int compare(QName n1, QName n2) {
		int answer = compare(n1.getNamespaceURI(), n2.getNamespaceURI());

		if (answer == 0) {
			answer = compare(n1.getQualifiedName(), n2.getQualifiedName());
		}

		return answer;
	}

	public int compare(Namespace n1, Namespace n2) {
		int answer = compare(n1.getURI(), n2.getURI());

		if (answer == 0) {
			answer = compare(n1.getPrefix(), n2.getPrefix());
		}

		return answer;
	}

	public int compare(CharacterData t1, CharacterData t2) {
		return compare(t1.getText(), t2.getText());
	}

	public int compare(DocumentType o1, DocumentType o2) {
		if (o1 == o2) {
			return 0;
		}
		else if (o1 == null) {
			// null is less
			return -1;
		}
		else if (o2 == null) {
			return 1;
		}

		int answer = compare(o1.getPublicID(), o2.getPublicID());

		if (answer == 0) {
			answer = compare(o1.getSystemID(), o2.getSystemID());

			if (answer == 0) {
				answer = compare(o1.getName(), o2.getName());
			}
		}

		return answer;
	}

	public int compare(Entity n1, Entity n2) {
		int answer = compare(n1.getName(), n2.getName());

		if (answer == 0) {
			answer = compare(n1.getText(), n2.getText());
		}

		return answer;
	}

	public int compare(ProcessingInstruction n1, ProcessingInstruction n2) {
		int answer = compare(n1.getTarget(), n2.getTarget());

		if (answer == 0) {
			answer = compare(n1.getText(), n2.getText());
		}

		return answer;
	}

	public int compareContent(Branch b1, Branch b2) {
		int c1 = b1.nodeCount();
		int c2 = b2.nodeCount();
		int answer = c1 - c2;

		if (answer == 0) {
			for (int i = 0; i < c1; i++) {
				Node n1 = b1.node(i);
				Node n2 = b2.node(i);
				answer = compare(n1, n2);

				if (answer != 0) {
					break;
				}
			}
		}

		return answer;
	}

	public int compare(String o1, String o2) {
		if (o1 == o2) {
			return 0;
		}
		else if (o1 == null) {
			// null is less
			return -1;
		}
		else if (o2 == null) {
			return 1;
		}

		return o1.compareTo(o2);
	}
}

/*
 * Redistribution and use of this software and associated documentation ("Software"), with or without modification, are
 * permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions must also contain a
 * copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived from this Software without prior written
 * permission of MetaStuff, Ltd. For written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may "DOM4J" appear in their names without prior
 * written permission of MetaStuff, Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
